1. Field of the Invention
This invention pertains to the general field of equipment for cleaning wafers, finished semiconductors and related components in the electronic industry. In particular, it provides a new and improved machine that allows the steps of cleaning, rinsing and drying to be carried out in the same chamber within the apparatus of a single work station.
2. Description of the Prior Art
Wet processing in the semiconductor industry requires washing of the semiconductor components to either interrupt and neutralize the action of the etching agents or to remove other residues. This is typically carried out manually or automatically is several stages whereby unit carriers are exposed to a neutralizing/washing chemical, rinsed and dried in different holding tanks. These stages require the units to be handled and moved from tank to tank, where each function is carried out. This procedure is costly because of the repeated manipulation of the product and because of the space requirements for housing and operating multiple-station equipment.
The neutralizing agents currently used consist of aqueous solutions of highly effective cleaning chemicals, such as the product sold by the Altos Group, Inc. of Glendale, Ariz., under the trademark "AQ-1534," which have replaced the toxic and environmentally undesirable chloro-fluoro-carbons originally used in the semiconductor industry. After rinsing with purified water, such as water produced by deionization or reverse osmosis, the semiconductors in the units need to be dried before proceeding to the next process phases of manufacturing. Typically, drying may be accomplished by blowing a heated inert gas or air into the container holding the wafers (air knife drying) to cause the vaporization of all water residue remaining on them. This process is expensive and inefficient because of the energy used to heat and blow the drying medium, and sometimes it is ineffective because of the difficulty of removing moisture from wet surfaces in contact with fixturing. In addition, the moisture removal is difficult to quantify and control to a constant level within acceptable product specifications.
Other drying processes rely on the hygroscopic properties of alcohols to extract moisture from the rinsed wafers. The semiconductor wafers are rinsed in alcohol and then dried, relying on the high volatility of the alcohol to obtain complete removal of the alcohol-water mixture. Because of the azeotropic properties of the alcohols normally used, though, complete water removal is hard to achieve. Moreover, the process is inherently dangerous because of alcohols' flammability and wasteful because used alcohol solutions must be discarded at significant environmental burden and production cost.
Therefore, there remains a need for a single-station piece of equipment that utilizes non-toxic aqueous cleaning solutions and purified water to clean and rinse semiconductor components, and that causes the material to dry inexpensively, effectively and efficiently, wherein all steps are carried out sequentially in a single compact machine. The present invention is directed at fulfilling all of these functions in the same machine by providing a cleaning system, a purified water rinsing system, and a vacuum drying system all connected to the same process chamber.